1. Field of Invention
This invention relates to stethoscopes, specifically to an improved means for monitoring two different sound sources simultaneously.
2. Description of Prior Art
French Patent 558,302 to Scheffler (1923) shows a stethoscope with two sensors or chest-pieces, one connected via a conducting tube to the left ear and the other to the right ear. This device cannot be converted for monophonic listening, i.e., with a single tube and chest-piece; and the user is therefore compelled to have both tubes dangling from his neck at all times. French Patents 580,538 to dePauw (1924), 649,886 to Guery (1928), with addition No. 36,027 (1930), 666,401 to Wilenkin (1929), 715,545 to Hardt (1931), and U.S. Pat. Nos. 1,811,558 to Porter (1931), 1,853,951 to Zala (1932), 2,209,164 to Kerr (1940), 4,706,777 to Baumberg (1987), all suffer from the same disadvantages. The stethoscope shown in U.S. Pat. No. 4,997,055 to Grady (1991) shows a common conducting tube, thus abolishing any possibility of differential or stereophonic auscultation, whereby sounds from two sources such as the lungs can be compared.